The challenge of testing high density MPO/MTP connectivity in data centers and plug-and-play networks is still being perfected. Recently, manufacturers have been working to develop new tools to speed the testing of mass connectors as the adoption of MPO connectors skyrockets in data centers where it's being for use in 40 and 100 GB connections.
FiberNext of Concord, New Hampshire, has marketed a prior art MPO switch device that allows all fibers of an MPO cable to be tested in a single direction. As shown in FIGS. 1A and 1B, the prior art MPO switch device includes a single SC Input port that connects the switch to a test device, such as an optical time-domain reflectometer (OTDR), optical fault locator (FL), or other fiber optic test device commonly utilized in the art. The combined test device and MPO switch form the prior art test system. The prior art MPO switch device also includes an MPO port that connects the device to the cable under test through the use of a test lead and MPO adaptor. FIG. 1B diagrams the operation of the prior art switch device, which includes a series of internal switches that direct the light from the test device to the fiber to be tested. These switches are controlled by a user input, which allows the user to select the fiber to be tested, and a display, such as an LCD display or a series of lights, provide a visual indication of which fiber is being tested.
In operation, the prior art MPO switch device is attached to the MPO cable to be tested and all fibers are individually tested in a single direction. However, in data applications, the MPO cable is used bi-directionally and must typically be tested in both directions. In these applications, odd numbered fibers, which terminate in ports 1, 3, 5, 7 9 and 11 in FIG. 1B, are used in one direction. Even numbered fibers, which terminate in even numbered ports 2, 6, 8 10 and 12 in FIG. 1B, are used in the opposite direction. Accordingly, once the odd numbered fibers are tested in one direction, the test device and MPO switch device must be disconnected and reconnected to the other end of MPO cable to test the even numbered fibers. This process can be time consuming, especially in large data center applications where thousands of cables need to be quickly and effectively tested. Accordingly, it has been common practice to use two prior art test stems, one at each end of the MPO cable under test. This is expensive and requires the results received by the two test devices to be run through specialized software that combines both into a single test result.
One potential way to more quickly test cables in both directions without the use of two test systems is to utilize a multipath MPO switch with a feedback loop cable at the end of the cable under test. This potential solution is shown in FIG. 2, which shows an MPO switch device having two SC ports A and B, each capable of sending and receiving signals, in communication with a similar series of switches as was shown in FIG. 1B. Because the internal switches are in a set position and cannot be set to both transmit and receive singles, a series of feedback loop cables are attached to the ports such that light being transmitted from SC port A through the upper set of switches is then returned through the lower set of switches to SC port B. Thus, for example, fibers 1 and 12, 3 and 10, and 5 and 8 can be simultaneously tested. The test cables at the SC ports are then removed and reattached to the opposite ports and light is then transmitted from SC port B through the lower set of switches is then returned through the upper set of switches to SC port A, which allows the remaining fibers to be tested in both directions. Although this saves some time and does not require two separate test systems, it still requires the test device cables to be removed and reattached between sets of test, which introduces the potential for contamination and skewing of the test results. More importantly, it does not allow adjacent ports to be tested simultaneously, which means that the entire test must be completed to determine whether a single send/receive pair of fibers are operational.
Therefore there is a need for an improved MPO switch that allows an MPO cable to be bi-directionally tested using a single test system without the need for reattaching test system cables and without the need to test all fibers in order to determine whether adjacent pairs of fibers are operational.